Hemostatic paste and methods of making thereof

ABSTRACT

The present invention is directed to a flowable hemostatic paste comprising a crosslinked carboxymethyl cellulose and at least one non-toxic dispersant. More specifically the present invention relates to a hemostatic paste containing citric acid cross-linked CMC, which is suspended or dispersed as a powder in a mixture of a first non-toxic glycerol-containing hygroscopic dispersant and a second non-toxic alcohol functionalized dispersant comprising propylene glycol or 1,3-butanediol.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of co-pending U.S. application Ser. No.16/055,433 filed Aug. 6, 2018, which claims benefit of Chinese PatentApplication Number CN 201810851056.6, filed Jul. 20, 2018, the completedisclosure of which is hereby incorporated herein by reference for allpurposes.

FIELD OF THE INVENTION

The present invention relates generally to agents and materials forpromoting hemostasis and tissue sealing and, more particularly, to fastswelling, highly absorbent hemostatic composition in a form of a pastecomprising a mixture of crosslinked carboxymethyl cellulose with one ormore dispersants, and to methods for manufacturing and using suchhemostatic composition.

BACKGROUND

In a wide variety of circumstances, animals, including humans, cansuffer from bleeding due to wounds or during surgical procedures. Insome circumstances, the bleeding is relatively minor, and normal bloodclotting functions in addition to the application of simple first aidare all that is required. In other circumstances, substantial bleedingcan occur. These situations usually require specialized equipment andmaterials as well as personnel trained to administer appropriate aid.

Bleeding during surgical procedures may manifest in many forms. It canbe discrete or diffuse from a large surface area. It can be from largeor small vessels, arterial (high pressure) or venous (low pressure) ofhigh or low volume. It may be easily accessible or it may originate fromdifficult to access sites. The control of bleeding is essential andcritical in surgical procedures to minimize blood loss, to reducepost-surgical complications, and to shorten the duration of the surgeryin the operating room. The selection of appropriate methods or productsfor the control of bleeding is dependent upon many factors, whichinclude but are not limited to bleeding severity, anatomical location ofthe source and the proximity of adjacent critical structures, whetherthe bleeding is from a discrete source or from a broader surface area,visibility and precise identification of the source and access to thesource.

Conventional methods to achieve hemostasis include use of surgicaltechniques, sutures, ligatures or clips, and energy-based coagulation orcauterization. When these conventional measures are ineffective orimpractical, adjunctive hemostasis techniques and products are typicallyutilized.

To address the above-described problems, materials have been developedfor controlling excessive bleeding or as adjuncts to hemostasis. TopicalAbsorbable Hemostats (TAHs) are widely used in surgical applications.TAHs encompass products in various forms, such as based on woven ornon-woven fabrics or sponges, and are typically made of at leastpartially resorbable materials, ranging from natural to syntheticpolymers and combinations thereof, including lactide-glycolide basedco-polymers such as polyglactin 910, oxidized cellulose, oxidizedregenerated cellulose (ORC), gelatin, collagen, chitin, chitosan, starchetc. Gelatin is used in various forms with or without a topical thrombinsolution. Also, widely used are biologically active topical hemostaticproducts (topical thrombin solutions, fibrin sealants, etc.) and avariety of synthetic topical sealants.

To improve the hemostatic performance, scaffolds based on the abovementioned TAH materials can be combined with biologically-derivedclotting factors, such as thrombin and fibrinogen.

Due to its biodegradability and its bactericidal and hemostaticproperties, oxidized cellulose, as well as oxidized regeneratedcellulose has long been used as a topical hemostatic wound dressing in avariety of surgical procedures, including neurosurgery, abdominalsurgery, cardiovascular surgery, thoracic surgery, head and necksurgery, pelvic surgery and skin and subcutaneous tissue procedures.Many methods for forming various types of hemostats based on oxidizedcellulose materials are known, whether made in powder, woven, non-woven,knit, and other forms. Currently utilized hemostatic wound dressingsinclude knitted or non-woven fabrics comprising oxidized regeneratedcellulose (ORC), which is oxidized cellulose with increased homogeneityof the cellulose fiber.

Fibrinogen and thrombin are critical proteins involved in achievinghemostasis after vascular injury and essential to blood clot formation.Fibrinogen and thrombin can be combined in powder form or in anon-aqueous suspension, without initiating a typical clotting reaction,thus preventing the formation of a fibrin clot until the proteins arehydrated in an aqueous medium or other liquid environment in which theproteins are soluble. An admixture of these proteins in powder form havea variety of potential biomedical applications including topicalhemostasis, tissue repair, drug delivery, etc. In addition, an admixtureof these proteins may be loaded onto a carrier or substrate, or othermedical device, in powder form to form a product that may be used forexample as a hemostatic device.

Fibrin sealants, also known as fibrin glue, have been in use in theclinic for decades. Oftentimes, fibrin sealant consists of two liquidcomponents, a fibrinogen comprising component and a thrombin comprisingcomponent, which are stored frozen due to their inherent instability.Sometimes fibrin sealant products consist of two freeze driedcomponents, which require reconstitution immediately prior to use anddelivery by a conjoined syringe or other double-barreled deliverydevice. Freeze dried formulations are typically stable, but thefibrinogen component is difficult to reconstitute. Many hemostaticformulations currently available on the market or in development utilizelyophilized fibrinogen, frequently in combination with lyophilizedthrombin, with hemostatic formulations applied in the form of drypowder, semi-liquid paste, liquid formulation, or optionally disposed ona supporting scaffold such as absorbable fabric scaffold.

To provide dressings with enhanced hemostatic and tissue sealing andadhering properties, therapeutic agents, including, but not limited to,thrombin, fibrin and fibrinogen have been combined with dressingcarriers or substrates, including gelatin-based carriers,polysaccharide-based carriers, glycolic acid or lactic acid-basedcarriers and a collagen matrix.

U.S. Pat. No. 8,858,969, entitled Hemostatic compositions, devices, andmethods, discloses a hemostatic device comprising: a containercomprising a bottle, vial, canister, tube, or reservoir with an interiorenclosure which contains a flowable hemostatic composition comprising aclay dispersed in an aqueous medium; wherein at least about 50% of theclay comprises particles with a particle size between about 1 nm and 10μm; wherein the composition is a liquid which is substantially free ofvisible clay particles such that an appreciable amount of the clayparticles does not settle from the liquid upon standing for at leastabout 12 hours; and wherein the composition is sterilized; and adispensing component in fluid communication with the container; whereinthe device is configured so that the dispensing component is capable ofdispensing the hemostatic composition from the container directly to ableeding area of an animal or person.

U.S. Patent Publication No. 2014/0369991, entitled Formulations forWound Therapy discloses a pharmaceutical composition comprising anabsorbable carrier of a biocompatible, biodegradable polymer anddispersed, at least partially through or on said absorbable carrier,microparticles comprising fibrinogen in an amount of from about 0.1-15mg/cm² and/or microparticles comprising thrombin in an amount of fromabout 0.01 to 500 IU/cm², wherein the microparticles further comprise aglassy carrier.

U.S. Patent Publication No. 2016/0206773, entitled Composition andMethod for Stopping Hemorrhage, Infection, and Accelerating Healing inVarious Types of Wound or Burns discloses a composition, comprising: ahydrogel matrix comprising at least one polymer cross linked, via ionicor covalent bonding, with both hyaluronic acid and alginic acid, whereinthe at least one polymer is selected from the group consisting ofchitosan, poly L-Lysine, or a combination thereof.

U.S. Pat. No. 9,265,858, entitled Dry haemostatic composition disclosesa method of preparing a dry composition suitable for use in haemostasisand wound healing, comprising the sequential steps of: a) providing across-linked biocompatible polymer in powder form, one or more polyolsand an aqueous medium, wherein the one or more polyols are selected fromsugar alcohols and sugars; b) mixing the biocompatible polymer, the oneor more polyols and the aqueous medium to obtain a paste; and c)freeze-drying the paste to produce a dry composition, wherein the drycomposition is capable of reconstituting to form a substantiallyhomogeneous paste without mechanical mixing, wherein the dry compositioncomprises from 10% w/w to 60% w/w of one or more polyols.

U.S. Pat. No. 2,772,999, entitled Hemostatic surgical compositions anddressings discloses a surgical composition for coagulating bloodcontaining a hemostatic amount, at least about 2%, of cellulosederivative of the group consisting of free acid cellulose glycolic acidether and free acid cellulose hydroxypropionic acid ether having degreeof substitution at least about 0.5, and degree of neutralization in theapproximate range 0 to 60% but sufficiently low so that the freecarboxyl content of the cellulose is at least 0.5 per glucose unit.

U.S. Patent Publication No. 2004/0101548, entitled Hemostatic wounddressing containing aldehyde-modified polysaccharide discloses ahemostatic wound dressing, comprising: a substrate for contacting awound, said substrate comprising; a wound-contacting surface; and abiocompatible, aldehyde-modified polysaccharide, wherein said wounddressing is hemostatic.

European Publication No. EP1493451, entitled Hemostatic devices andmethods of making same discloses a composition, comprising:biocompatible, oxidized cellulose particles having an average designatednominal particle size of from about 0.035 to about 4.35 mm; and abiocompatible, porous water-soluble or water-swellable polysaccharidebinder component; wherein said composition is suitable for use in ahemostatic device.

U.S. Pat. No. 3,328,259, entitled Dressing for a wound containing ahemostatic agent and method of treating a wound discloses a dressing fora wound comprising a flexible body large enough to cover an open lesionas a dressing, said 40 body containing a water-soluble plasma-solublecellulose derivative having hemostatic and film-forming properties andhaving the property of combining with the plasma in a wound to form withsaid plasma an artificial water-insoluble eschar, said cellulosederivative being present in integral non-discrete form in said body andin proportions to cause said body to be effective in coagulating theplasma issuing from a moist lesion to which the dressing is applied.

U.S. Patent Publication No. 2007/0207180, entitled Syntheticpolypeptide-containing bioapplicable material and film-forming materialdiscloses a bioapplicable material containing a polypeptide, wherein thepolypeptide comprises a synthetic polypeptide having at least an aminoacid sequence represented by the formula: Pro-Y-Gly, wherein Yrepresents Pro or Hyp, and forming a collagen-like structure.

U.S. Patent Publication No. 2012/0070470, entitled Hemostaticcompositions, devices, and methods, discloses a blood-clotting agentcomprising: a composition comprising clay dispersed in a liquid medium,wherein the clay is less than about 10% by weight of the composition;and wherein the composition including the liquid medium and clay has aviscosity of about 1000 cP or less.

U.S. Patent Publication No. 2002/0197302, entitled Hemostatic polymeruseful for rapid blood coagulation and hemostasis discloses a method forarresting bleeding and inducing rapid blood coagulation and clotformation at a bleeding site, comprising applying a dry dressingcomprising a matrix containing a hemostasis-promoting amount of ahemostatic agent which accelerates blood coagulation and clot formationat an interface between a wound surface and hemostatic zone to saidbleeding site for a period of time sufficient to induce rapid bloodcoagulation at said site and removing the dressing after the blood atsaid bleeding site has clotted.

U.S. Patent Publication No. 2005/0226916, entitled Hemostatic polymeruseful for Rapid blood coagulation and hemostasis discloses a method forpromoting blood coagulation at a bleeding site in a mammal comprisingapplying to said bleeding site a composition comprising porous polymericspheres and allowing said blood coagulation to occur at said bleedingsite.

Chinese Patent Publication No. CN101001649A, entitled Haemostaticcomposition comprising hyaluronic acid discloses hemostatic composition,comprising a bioabsorbable material and hyaluronic acid (HA) or aderivative thereof.

U.S. Pat. No. 4,002,173, entitled A Diester crosslinked polyglucanhydrogels and reticulated sponges thereof relates to hydrogelcompositions of diester crosslinked polyglucans and a process for theirpreparation.

Chinese Patent Application Publication No. CN102379827A Toothpastecontaining dencichine and preparation method thereof relates to atoothpaste that has CMC is one of its components.

U.S. Patent Publication No. 2005/0037088, entitled Process of makingflowable hemostatic compositions and devices containing suchcompositions discloses a process for making a flowable hemostaticcomposition, comprising: introducing a volume of a biocompatible liquidinto a mixing vessel equipped with a means for mixing said liquid,introducing a volume of a biocompatible gas into said volume of liquidwhile said means for mixing is operating under conditions effective tomix said liquid and said gas together to form a foam comprising adiscontinuous gas phase comprising said gas substantially homogenouslydispersed throughout a continuous liquid phase comprising said liquid,introducing into said foam an amount of solid particles of abiocompatible polymer suitable for use in hemostasis and which issubstantially insoluble in said liquid; and mixing said foam and saidsolid particles together under conditions effective to form asubstantially homogenous composition comprising said discontinuous gasphase and said particles substantially homogenously dispersed throughoutsaid continuous liquid phase, wherein the ratio of said volume ofliquid, said volume of gas and said amount of solid particles iseffective to provide said substantially homogeneous composition withhemostatic properties, thereby forming said flowable hemostaticcomposition.

U.S. Patent Publication No. 2005/0284809, entitled Hemostaticcompositions and devices, discloses a plurality of packed particlescomprising interstitial pores having a pore volume and a median porediameter effective to provide improved absorption of physiologicalfluids or an aqueous media into said interstitial pores when placed incontact therewith, compared to a plurality of unpacked particles of thesame material, said particles comprising a biocompatible material andhaving a median diameter suitable for use in providing hemostasis to asite of a body of a mammal requiring hemostasis.

U.S. Pat. No. 7,083,806, entitled Wound gels, discloses a hydrogelcomprising a pre-crosslinked gellant, water, and a poloxamer, whereinthe concentration of said poloxamer is between 10 and 25% by weight ofthe hydrogel and the gellant comprises at least one cross-linked,superabsorbent polysaccharide, said hydrogel exhibiting thermallyinduced viscosification at a temperature between ambient and 35° C., andwherein said hydrogel has the capacity to absorb at least 50% furtherwater in addition to the water already present, specifying waterpresence in the hydrogel.

European Publication No. 1942117A1, entitled Derivatives of acidpolysaccharides discloses acid polysaccharides characterized by theconcomitant presence of partial esters with non-polysaccharidecarboxylic acids and esters between the acid groups of the initialpolysaccharide and the alcohol groups of the repetitive units, with theformation of crosslinking between the polysaccharide chains.

U.S. Pat. No. 9,353,191, entitled Method for producing hydrogels,discloses a polymer hydrogel consisting essentially of carboxymethylcellulose cross-linked with citric acid characterized by (a) a tappeddensity of at least 0.5 g/cm³; and (b) a media uptake ratio in simulatedgastric fluid/water (1:8) of at least about 50 at 37° C.

U.S. Pat. No. 8,658,147B2, Polymer hydrogels and methods of preparationthereof (also European Patent Publication No. EP2532685A1) discloses amethod of treating obesity in a subject in need thereof, comprising thestep of orally administering to the subject a therapeutically effectiveamount of a polymer hydrogel comprising carboxymethyl cellulosecovalently cross-linked with citric acid.

U.S. Pat. No. 5,905,092, entitled Topical antibiotic compositionproviding optimal moisture environment for rapid wound healing thatreduces skin contraction discloses a composition for the treatment ofwounds comprising: a topical semisolid which is capable of providing amoist environment for a wound by promoting increased water content inwounds becoming dry and promoting reduced water content in wounds havingexcess exudate, comprising vehicles, which are capable of incorporatingwater to at least about 30% of their initial application weight, whilealso being capable of retaining at least about 70% of their applicationweight for two hours when left on a non-absorbing surface; an antibioticformulation; and at least 60% by weight of water, wherein the topicalsemisolid comprises from about 10% to about 20% by weight of apolyhydric alcohol and from about 0.5% to about 10% by weight each oftwo or more gelling agents selected from the group consisting ofhydroxyethyl cellulose, hydroxypropyl cellulose, polyvinylpyrrolidone,cross-linked acrylic acid polymer, PVM/MA decadiene crosspolymer andammonium acrylates/acrylonitrogen.

U.S. Patent Publication No. 2013/0108682, entitled Wound Care ProductComprising a Cathelicidin Polypeptide, discloses a wound care productcomprising a wound care material and a polypeptide having wound healingproperties, wherein the polypeptide having wound healing properties is acathelicidin, or a fragment, variant or fusion thereof which retains, atleast in part, the wound healing activity of said cathelicidin.

U.S. Pat. No. 8,829,053, entitled Biocidal compositions and methods ofusing the same discloses an antimicrobial composition, comprising: atleast one polymeric biguanide in an amount of at least 0.05 weight %, achelating agent at a concentration of from 0.01 weight % to 1 weight %,and a vicinal diol component comprising at least one monoalkyl glycoland at least one monoalkyl glycerol, wherein a weight ratio of said atleast one polymeric biguanide and said vicinal diol component rangesfrom 1:0.05 to 1:500, wherein said antimicrobial composition kills atleast 99.99% of organisms in a biofilm within ten minutes of treatmentwith said antimicrobial composition.

U.S. Patent Publication No. 2014/0105950, entitled Haemostatic Materialdiscloses a haemostatic material comprising a haemostat agent and abioadhesive agent, wherein the haemostat agent is selected from the listconsisting of: oxidised regenerated cellulose, kaolin, gelatin, calciumions, zeolite, collagen, chitosan and chitosan derivatives.

An article “Novel Superabsorbent Cellulose-Based Hydrogels Crosslinkedwith Citric Acid” by Christian Demitri, et al., Journal of AppliedPolymer Science, Vol. 110, 2453-2460 (2008) discloses the preparation ofnew environmentally friendly hydrogels derived from cellulose and henceoriginating from renewable resources and characterized by biodegradableproperties. Two cellulose derivatives, sodium carboxymethyl cellulose(CMCNa) and hydroxyethyl cellulose (HEC), were used for superabsorbenthydrogel preparation. Citric acid (CA), a crosslinking agent able toovercome toxicity and costs associated with other crosslinking reagents,was selected in a heat activated reaction. Differential scanningcalorimeter (DSC), Fourier transform infrared spectroscopy (FTIR), andswelling measurements were performed during the reaction progress toinvestigate the CA reactivity with each of the polymers. Also, CMCNa/HECpolymer mixtures (3/1 w/w) crosslinked with CA were investigated andcompared with previous results.

There is a need in improved hemostatic forms and materials whichfacilitate ease of application and rapid onset of hemostasis.

SUMMARY OF THE INVENTION

The present invention is directed to a flowable hemostatic pastecomprising a crosslinked carboxymethyl cellulose (CMC) and at least onenon-toxic dispersant. Non-toxic means, for purposes of this application,a material that is generally regarded as safe according to one or morefood and/or drug related regulatory agencies, though not limited only tosuch GRAS materials now or in the future and may include other materialssharing similar safety characteristics and suitability for humanconsumption. The hemostatic paste is absorbent, swellable, andbiodegradable. CMC is preferably cross-linked by a polyfunctionalcarboxylic acid, wherein said acid is preferably selected from the groupconsisting of malic, tartaric, citric, malonic, succinic, glutaric,adipic acid and mixtures thereof.

In some embodiments, the hemostatic paste comprises 35% to 65% by weightof citric acid cross-linked CMC, which is suspended or dispersed as apowder in a mixture of a first non-toxic hygroscopic dispersantcomprising glycerol, preferably a substantially pure 100% glycerol, inthick liquid format, pharmaceutical grade, and a second non-toxicdispersant comprising propylene glycol, 1,3-Butanediol or mixturesthereof.

In some embodiments cross-linked CMC comprises a powder having averageparticle size less than 100 microns and the paste is substantially freeof water or is substantially anhydrous. In some embodiments, the pastefurther comprises a neutralizing alkaline agent.

According to some embodiments of the present invention, there isprovided a method of making a flowable hemostatic paste comprising thesteps of: cross-linking CMC by mixing CMC with citric acid in presenceof water and reacting CMC with citric acid at elevated temperature;Drying the cross-linked CMC; Milling the cross-linked CMC to a powderhaving average particle size of less than 100 microns; Adding glycerolinto the CMC powder, and mixing until a homogenous dough-like materialis formed; Adding propylene glycol to said dough-like material andmixing thoroughly; Thus forming said flowable hemostatic paste.

According to some embodiments of the present invention, there isprovided a method of using the hemostatic paste, comprising the stepsof: applying the hemostatic paste, optionally supported on a flexibleabsorbable sheet substrate, onto or into a bleeding tissue or wound.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 shows schematic pathway for synthesis of cross-linkedcarboxymethyl cellulose (CMC).

FIG. 2 is a photo showing hemostatic paste as it is expressed from atube onto a substrate.

FIG. 3 shows swelling of CMC-CA xerogels in plasma, saline, and water at1 min and 2.5 min after immersion.

FIG. 4 shows swelling of CMC based xerogels crosslinked by differentcarboxylic acids upon exposure to water at 1 min and 2.5 min afterimmersion.

FIG. 5 shows swelling of xerogels made by crosslinking of differentpolysaccharides by citric acid in comparative chart for swelling in DIwater, saline or porcine plasma.

FIG. 6 shows hygroscopic or water-free paste relative to pastecontaining 10% and 20% water.

FIG. 7 shows the hydrogel paste containing 5% and 10% of water in a cutopen dispensing tube.

FIG. 8 shows a chart presenting viscosities of different formulations ofthe instant hemostatic paste as a function of shear rate.

FIG. 9 is showing CMC-CA powder on animal model bleeding site comprisinga puncture wound.

FIG. 10 is showing the hemostatic paste precisely delivered to the woundsite.

FIG. 11 is showing CMC-CA powder applied on the puncture model.

FIG. 12 is showing SEM micrograph of CMC-CA powder formed hydrogel

FIG. 13 is showing the inventive hemostatic paste applied onto the liverpuncture model

FIG. 14 is showing the expressed hemostatic paste containing particlesize 100 μm 300 μm.

FIG. 15 is showing a micrograph of CMC-CA xerogel powder for particlesize <100 μm.

FIG. 16 shows the testing results of the hemostatic paste containingnon-cross-linked CMC (comparative example).

FIG. 17 shows the testing results of the hemostatic paste containingCMC-CA (inventive example).

FIG. 18 shows the testing results of the hemostatic paste containing CAcross-linked carboxymethyl starch (comparative example).

FIG. 19 shows the testing of the adhesion to the tissue.

FIG. 20 shows the inventive CMC-CA based hemostatic paste prior, duringapplication, and after application into liver punch model.

FIG. 21 shows the inventive CMC-CA based hemostatic paste applied tocommercially available Oxidized Regenerated Cellulose (ORC)-basednon-woven pad.

FIG. 22 shows the CMC-CA based hemostatic paste applied to commerciallyavailable Oxidized Regenerated Cellulose (ORC)-based non-woven pad andthe resulting composite prior to being tested for adhesion to a livertissue coupon, and after contacting with liver tissue coupon.

DETAILED DESCRIPTION

The present invention relates generally to agents and materials forpromoting hemostasis and tissue sealing and, more particularly, to fastswelling, highly absorbent hemostatic composition in a form of a pastecomprising a mixture of crosslinked carboxymethyl cellulose with one ormore dispersants, and to methods for manufacturing and using suchhemostatic composition.

The embodiments of the present invention further relate to fastswelling, superabsorbable, biodegradable hemostatic paste. In someembodiments, the hemostatic paste comprises at least three components.The first component comprises a xerogel powder that is synthesized bycrosslinking carboxymethyl cellulose (CMC) using polyfunctionalcarboxylic acids such as citric acid (alternatively malic, tartaric,citric, malonic, succinic, glutaric, adipic acid etc.). A xerogel isobtained when the liquid phase of a gel is removed by evaporation. Ittypically exhibits shrinkage of greater than (>) 90%.

Cross-linked CMC can form hydrogel when placed in contact with bodyfluids. A hydrogel is a network of polymer chains that are hydrophilic,sometimes found as a colloidal gel in which water is the dispersionmedium. The concentration of crosslinked CMC in the hemostatic pasteranges from about 35% to 65% weight by weight. The second componentcomprises a glycerol-containing dispersant at 10% to 30% weight byweight. The third component comprises an alcohol-functionalizeddispersing agent at 10% to about 30% weight by weight, such as propyleneglycol or 1,3-Butanediol. The hemostatic paste is biocompatible to treatmild or moderate bleeding.

According to one embodiment, a fast swelling, superabsorbable,biodegradable hemostatic paste comprises: carboxymethyl cellulosecrosslinked by citric acid (or similar polyfunctional carboxylic acide.g. malic, tartaric, citric, malonic, succinic, glutaric, adipic acid)35% to 65% which is suspended or dispersed as a fine powder, asdemonstrated in the examples, in a mixture of a first non-toxicglycerol-containing, hygroscopic dispersant and a second non-toxicalcohol-functionalized dispersant, preferably comprising propyleneglycol or 1,3-Butanediol. A paste means, for purposes of thisapplication, a flowable material that has sufficient viscosity andcohesion to maintain a continuous, singular form at room temperaturewhen placed upon a flat, unconstrained flat surface. A pile of sand orsimilar collection of particulates would not be a paste as theindividual particles lack sufficient cohesion with one another. Theinventive formulation is substantially free of water or anhydrous. Insome embodiments, both dispersants are hydrophilic.

Dried cross-linked CMC xerogel has three-dimensional crosslinkedpolymeric network that are capable of absorbing large quantities ofwater, saline or physiological liquid forming hydrogels. The powerfulosmotic action dehydrates and gels the blood upon contact and swellingto more than 20 times of the dry xerogel volume to fill up a wound andproduce a “back pressure” in the confined wound space to simulatetamponade effect and enhance the natural clotting process. Theflowability and flexibility of the inventive paste also ensure itsaccess to narrow spaces and its application to uneven surfaces, makingit a useful material to address the intra-operational bleeding oroozing. The instant paste is particularly suitable for hard to accesswounds such as tissue crevice or cavity bleeding.

In an alternative embodiment, the inventive paste can also be used inconjunction with a backing, pad, scaffold, or matrix to providemechanical strength to cover the wound surface. In this case, theinstant paste is supported on a pad for ease of application ortamponade.

In another embodiment, the instant hemostatic paste can be employed fora timed or delayed release of active agents e.g. as a drug-deliveryvehicle. The composition can incorporate growth factors, antibiotics,local anesthetics, and any agents useful to improve wound healing,prevent infection or relieve pain. By incorporating coagulationactivators, platelet activators or blood vessel constrictors,fibrinolytic function inhibitors, etc., including thrombin, fibrinogen,etc., the hemostatic effect of the paste could be further improved.

According to the inventive embodiments, the instant hemostatic paste isanhydrous and hygroscopic. It can absorb liquid, such as water, blood,etc., and expands to form hydrogel within seconds, such as within 5, 20,30, 50, 120, 300 seconds, more preferably within 5-30 seconds.

The xerogel powder particles are suspended in dispersant components ofthe hemostatic paste. The resulting paste is flowable, and can bedeposited into/onto uneven surfaces or into narrow spaces.

The main component of the paste forming the xerogel, is carboxymethylcellulose, crosslinked by citric acid, resulting in an increasedmechanical stability. Several polysaccharides show a high absorptionability in the unmodified state, but these have the disadvantage thatthe swelling occurs only in warm water and that dissolution can takeplace. Such unmodified/uncross-linked polysaccharides have lowmechanical stability and can undergo degradation, and/or retrogradation,and/or and syneresis (contraction of a gel accompanied by the separatingout of liquid).

The inventors observed that advantageously cross-linked CMC particles donot absorb the dispersants which are anhydrous but hydrophilic, glyceroland propylene glycol, despite glycerol and propylene glycol beinghydrophilic, while particles were still capable to rapidly absorbingblood, plasma, water, bodily fluids.

Without wishing to be bound by any theory, the non-aqueoussolvents/carriers/dispersants are outside of the crosslinked networkparticles and should not influence their ability to absorb liquids. Theabsorption would appear to be maximized by eliminating pre-swelling orpre-load. The particles do not swell or absorb the selectedsolvents/carriers/dispersants but can quickly swell when provided withplasma and absorb the greatest % of plasma components. Presence ofcompounds such as sorbitol in the cross-linking reaction solution mayresult in the sorbitol would become entrapped within the cross-linkednetwork. The entrapped sorbitol would then help to prevent excessivecrosslinking by taking up space for a network link and could also alterthe hydrophilicity of the overall particle by attracting water into thecrosslinked particles. Thus, it is preferred that the present system isdevoid of sorbitol or similar chemical moieties and/or excipients. Theselected solvents/carriers/dispersants should not shield the crosslinkednetwork particles from the plasma components that are intended to beabsorbed.

Example 1. Making of the Hemostatic Paste and Paste Composition

Referring to FIG. 1, one schematic pathway for synthesis of cross-linkedcarboxymethyl cellulose (CMC) is shown, with initial reagents being CMCsodium salt (CMC-Na) and Citric acid (CA), with the reaction carriedout, as an example only, at 140° C. for 25 min, resulting in thecross-linked CMC (CMC-Na-CA). Dried cross-linked CMC, which can bereferred to as a xerogel or dried, compact hydrogel, is then used as acomponent for forming the inventive highly absorbent (super absorbent)hemostatic paste.

In one embodiment, CMC was cross-linked by citric acid as follows. Thesodium salt of the CMC (supplier: Shanghai Aladdin biochemicalTechnologies Co. Ltd, China) was used for the synthesis of thehydrogels. A cross-linker ratio Fz of 0.025 was used. Fz is defined asthe amount of cross-linking agent divided by the amount ofanhydroglucose units. The cross-linking agent was first dissolved indistilled water and then thoroughly homogenized with the CMC, resultingin a homogeneous dough-like product. The dough-like product was thenchopped into small chunks. The product was heated at 140° C. for 25 minin a preheated oven to accomplish cross-linking. The obtained productwas dried at 70□ overnight and then ground to an average particle sizeof below 100 μm.

The resulting cross-linked CMC powder was then mixed with dispersants asfollows. Glycerol (in some embodiment containing 1% of NaOH) was addedinto powder, and mixed/stirred until all powder particles are coated byglycerol, forming a dough-like paste. Then propylene glycol is added tothe above paste, and mixed/stirred, to form the final, flowablehemostatic paste.

Sodium hydroxide is added into glycerol to neutralize the free acid.Sodium hydroxide component is believed to chemically stabilize theformulation by neutralizing the unreacted citric acid and polycarboxylicgroup of the carboxymethyl cellulose. Undesirably, the carboxylic groupin the citric acid and the crosslinked CMC might react with the hydroxylgroup in the propylene glycol resulting in an esterification reactionwhich may cause the hardening of the paste over time. Sodium hydroxidefurther is expected to improve the water absorption and swellingproperty of the cross linked carboxymethyl cellulose.

According to one embodiment, glycerol was used with about 1% of sodiumhydroxide dissolved in it to adjust pH. NaOH was added to glycerol atelevated temperature, such as 65° C., resulting in rapid dissolution andno precipitating out upon cooling to ambient temperature of 20-25° C.The pH of the glycerol was measured as 5.7 with NaOH added, prior toadding NaOH pH was 5.18.

Without wishing to be bound by any theory, additions of sodium hydroxideenable improved performance and stability of the final hemostatic paste.The —COOH group in the CMC-CA may tend to react with —OH group ofpropylene glycol and cause limited stability of the paste. Use of NaOHthen enables formulation which has the —COOH groups at least partiallyneutralized. However simply adding NaOH into the CMC-CA paste will notbe practical or possible because with such small amount of NaOH powder,it is virtually impossible to uniformly and homogenously disperse itthrough the CMC-CA powder matrix. On the other hand, dissolving NaOH inwater and then adding it as aqueous solution also will not work as thepaste formulation needs to be anhydrous. Even small quantities of waterpresent in contact with the CMC-CA powder could cause the powder toswell and may compromise the ability to quickly absorb blood whenapplied to the wound.

Advantageously, for the inventive hemostatic paste, the dispersant isanhydrous. According to embodiments of the present invention, for thedispersant selection, the key requirements are non-toxic, anhydrous,able to dissolve NaOH, and biocompatible. While NaOH was found to bevery poorly soluble at room temperature in glycerol (i.e. it wasexceedingly difficult to dissolve NaOH at room temperature) theinventors discovered that NaOH can be easily dissolved in glycerol atabout 65° C. and then will not precipitate upon cooling. Table 1 showsthe solubility of NaOH in glycerol as a function of temperature. Fulldissolution was observed at least 65° C.

TABLE 1 Dissolution temperature of NaOH in glycerol 100 mg of NaOHpowder mixing with 10 g of glycerol Temperature ° C. Dissolving or not25 no 35 no 45 no 55 no 65 yes

After dissolving 1% of NaOH in glycerol, the inventors used thissolution to partially neutralize the formulation, improve stability andswellability. As discussed above, pH was adjusted from 5.18 to 5.71.

Referring to Table 2, Composition of hemostatic paste is presented. Allcomponents are biocompatible.

TABLE 2 Composition of the hemostatic paste Weight % Weight to prepareCompound Function concentration 10 g of paste, g Cross-linked CMCAbsorbent 53.1% 5.31 powder (CMC-CA) particles 1% NaOH in glycerolDispersant 26.5% 2.65 Propylene glycol Dispersant 20.4% 2.04 TOTAL: 10010 g

Referring to FIG. 2, appearance of the inventive hemostatic paste isshown as it is expressed from a tube onto a substrate. The paste isanhydrous, flowable and ready-to-use. It can be used by directlyapplying it to a bleeding site, or be used together with a hemostaticgauze or substrate, absorbable or not absorbable.

Comparisons of hemostatic paste with only one dispersant to the instanthemostatic paste are presented below. Hemostatic paste formulated withglycerol only, without the second dispersant (such as propylene glycolor 1,3-Butanediol), will have very high viscosity and the compositionwith only glycerol has poor absorbing properties. Hemostatic pasteformulated with the second dispersant propylene glycol or1,3-Butanediol, without the first dispersant (glycerol) would result ina poor dispersing effect of crosslinked CMC. Precipitation was observedwithin short time. However, Propylene glycol, as a water-miscibleco-solvent, does not inhibit the crosslinked CMC from rapidly absorbingliquid. With both glycerol and the propylene glycol in a certain range,the viscosity of the paste can be tuned to ranges convenient forexpressing and storage while no precipitation was observed, while at thesame time properties of crosslinked CMC of rapidly absorbing liquids wasmaintained. Thus, it was shown that the presence of two dispersants, asdescribed, was critical for the hemostatic paste handling, storage, andperformance.

Advantageously, the present hemostatic paste compositions are anhydrous,with the water absence critical to performance.

Example 2. Swelling Properties of Cross-Linked CMC and OtherPolysaccharides

For swelling testing, 1 gram of xerogel was immersed in excess DI water,saline or porcine plasma at room temperature for certain period to reachswelling equilibrium. At time intervals of 1, 2.5 min, swollen sampleswere separated from the unabsorbed DI water, saline or plasma byfiltering through a 100-mesh screen. Swelling percent at each time pointwas calculated using the following formula Equation: SP=100 (Mt−Md)/Mdwhere SP is the swelling percent, Mt and Md are the weights of swollenhydrogel particles at time t and dry xerogel particles, respectively.

Referring to FIG. 3, swelling of CMC-CA xerogels is shown in plasma,saline, and water at 1 min and 2.5 min after immersion, with significantswelling of the order of 1900-2700% at 1 min and 2500-3600% at 2.5 minobserved experimentally.

Referring to FIG. 4, swelling of CMC based xerogels crosslinked bydifferent carboxylic acids is compared upon exposure to water at 1 minand 2.5 min after immersion. The data show that xerogels made bycrosslinking CMC with Citric acid (CMC-CA) has strongest swellingcapacity with significant swelling of the order of 2900% at 1 min and4200% at 2.5 min observed experimentally, vs. somewhat lower swellingfor xerogels made by crosslinking CMC with Succinic acid, Malic acid orGlutaric acid (CA: Citric acid; MA: Malic acid; SA: Succinic acid; GA:Glutaric acid).

Referring to FIG. 5, swelling of xerogels made by crosslinking ofdifferent polysaccharides by citric acid is presented in a comparativechart for swelling in DI water, saline or porcine plasma. As can be seenfrom the data presented, in water, xerogels made from carboxymethylchitosan showed highest swelling property. However, in saline andplasma, xerogel made from carboxymethyl cellulose showed highestswelling property.

Example 3. Criticality of Water Absence

The criticality of water absence was further evaluated by testing theinstant hemostatic paste with additions of water. It was shown that at5% and above concentration of water, properties of the hemostatic pastehave degraded. Referring to FIG. 6, hygroscopic or water-free paste isshown as flowable, semi-liquid material, while paste containing 10%, 20%water is shown as clumped, crumbly material.

Referring to FIG. 7, The flowability of the hydrogel paste is reducedwhen containing water, potentially due to volume expanding of hydrogelparticles, especially over time. The paste containing 5% of water isshown in a cut open dispensing tube, with properties making it hard todispense. The paste containing 10% water is shown as rubber-likesolidified material which will not be possible to express from the tube.

Thus, the water content can compromise the flowability of the instanthemostatic paste with the water content is inversely proportional to theflowability of the paste. Thus, it is preferred that the paste issubstantially water free, or has water content 0-5%, such as 0, 0.5, 1,2, 3, 5%.

Example 4. Evaluations of Optimal Concentration Ranges and OptimalRatios

A range of different formulations of the hemostatic paste was furtherevaluated. Referring now to Table 3, several formulations of thehemostatic paste are presented, with all having 53% by weight CMC-CA andvariable amounts of glycerol, propylene glycol (PG) dispersants.

TABLE 3 Formulations of hydrogel paste CMC- propylene CMC PG GlycerolFormulation CA/g glycol/g glycerol/g % % % description 1 5 0.00 4.44 53%0.0% 47% Only Glycerol 2 5 2.22 2.22 53% 24 24 PG:Glycerol 1:1 3 5 1.782.66 53% 19 28 PG:Glycerol 1:1.5 4 5 1.48 2.96 53% 16 31 PG:Glycerol 1:25 5 1.92 2.52 53% 20 27 PG:Glycerol 1:1.3 6 5 4.44 0.00 53% 47 0.0 OnlyPG 7 5 2.66 1.78 53% 28 19 PG:Glycerol 1.5:1 8 5 2.98 1.48 53% 32 16PG:Glycerol 2:1

Referring to FIG. 8, viscosities of different formulations of theinstant hemostatic paste are presented as a function of shear rate. Thedata was measured by Discovery HR-3 hybrid rheometer (TA instruments),using flat plate, steady shear test. It was discovered that for ahemostatic paste with good performance, the viscosity should rapidlydecrease while the shear force is increasing, corresponding to ease ofexpressing the paste from the storage container when being applied. Thepaste should also have high viscosity at stationary state, which makesit stay at where it is applied instead of flowing away (run-off). Eightdifferent formulations were tested to evaluate the appropriate range ofthe dispersants. According to the viscosity data and the performance ofpaste on the animal tissue, the range between PG-glycerol 1:0.5 toPG-glycerol 1:2 is the best performing range. Referring to Table 3,showing eight different formulations tested, for 100 g of paste, the CMCpowder represents 53% (w/w) of the total weight and that of Glycerol isbetween 16%-31% (w/w).

A range of compositions with variable ratios of glycerol and propyleneglycol were further evaluated and optimized. Referring to Table 4,properties of the resulting hemostatic paste are shown as a function ofthe composition.

TABLE 4 Glycerol and the propylene glycol ratio optimization.Appearance/ Propylene glycerol/ CMC-CA/ flowability/ CMC- GlycolGlycerol, CMC- PG Glycerol PG glycerol viscosity CA, g (PG), g g CA % %% RATIO RATIO of paste 1 8.4 6.3 0 57 43 0 0 1.33 “thin” 2 5.76 2.3 4.347 17 35 1.87 0.87 “Thick” 3 13 5 6.55 53 20 27 1.31 1.13 “moderate”scale 61.26 23.5 30.62 53 20 27 1.30 1.13 “Moderate” up

The terms “Thick”, “Thin”, “Moderate” above are based on flowability andappearance. The “thick” sample is almost un-flowable, and will notconform well to the irregular shape of wound site. The “thin” sample istoo liquid resulting in easy to runoff and not staying in place.“Moderate” compositions were found to be acceptable in that they can beeasily shaped, conformed well to the wound site, and resulted in norunoff.

Compositions containing about 49-55% of CMC-CA are preferred.

Compositions containing about 18-30% of glycerol are preferred.

Compositions containing about 15-30% of propylene glycol are preferred.

Compositions characterized by the ratio of glycerol to propylene glycol(by weight) of about 1-1.5 are preferred.

Compositions characterized by the ratio of CMC-CA to glycerol (byweight) of 0.9-1.25 are preferred.

Example 5. Dispersants Comparisons

In some embodiments, three different dispersants were compared:propylene glycol, dipropylene glycol, 1,3-Butanediol, as shown in Table5. At the same ratio, the dipropylene glycol paste is stickier and lessuseable than the other two. The flowability of the dipropylene glycolpaste was not as good as paste formulated with propylene glycol and the1,3-Butanediol.

TABLE 5 Dispersants comparisons Actual weight/g CMC-CA 5.31 glycerol2.94 propylene glycol 2.28 RESULT: Paste with moderate viscosity,acceptable flowability CMC-CA 5.31 glycerol 2.94 dipropylene glycol 2.31RESULT: Paste with sticky viscosity, not acceptable CMC-CA 5.31 glycerol3.04 1,3-Butanediol 2.3  RESULT: Paste with moderate viscosity,acceptable flowability

Example 6. Paste-Powder Comparisons

CMC-CA powder was further compared to the inventive paste inperformance, and the advantages in performance demonstrated showing thatthe flowable viscous paste format has advantages over the same materialas a powder. According to an animal study result, although CMC-CA powderwas also effective stopping bleeding in a puncture model, powder hasexhibited two disadvantages comparing with the paste:

Powder was not possible precisely deliver, and as it was sprayed, thecovering range was somewhat wide, not as suitable for a confined woundspace. Referring to FIG. 9, showing CMC-CA powder on animal modelbleeding site comprising a puncture wound, CMC-CA powder covers a widesurface area surrounding the puncture wound, resulting in broad coveragebut lack of precise delivery. Referring to FIG. 10, showing the instanthemostatic paste delivery, paste is shown to be precisely delivered tothe wound site, and does not block the vision. Referring to FIG. 11,CMC-CA powder applied on the puncture model shows less cohesivenessbetween particles and blood can break through the gaps between thepowder particles.

Referring to FIG. 12, SEM micrograph of CMC-CA powder (<100 μm) formedhydrogel is presented. The hydrogel formed by powder shows that thereare still gaps, crevices within the hydrogel matrix. Through which bloodcan seep through or leak through.

Referring to FIG. 13, the inventive hemostatic paste is shown appliedonto the liver puncture model, resulting in hemostasis. Paste format hashigher cohesiveness among the particles compared with powders. No bloodbreak-through through the paste was observed.

Example 7. CMC-CA Xerogel Particulate Properties

CMC-CA powder with particle size 100 μm˜300 μm was observed to result insolid powder in the paste started to precipitate during storage. Whentube contained the hemostatic paste was squeezed to dispense the paste,dispersants came out first, and the powder settled to the bottom of thetube, and was hard to dispense, rendering a portion of the paste dry andnon-flowable. However, powder particle size <100 μm such detrimentalperformance was not observed, with the paste kept homogeneous throughoutstorage, and none or minimal sedimentation was observed. Referring toFIG. 14, particle size 100 μm˜300 μm is seen rendering a portion of thepaste dry and non-flowable, due to precipitation.

CMC-CA powder was further characterized showing the shape of theparticles is irregular, because of blender used to mill the powder.Referring to FIG. 15, Micrograph of CMC-CA xerogel powder is shown forparticle size <100 μm.

Example 8. Hemostatic Paste Properties in Heparinized Animal Model:Hemostasis Data for Cross-Linked and Non-Cross-Linked CMC

The hemostatic paste formulated as described in Example 1 was furtherevaluated in heparinized liver punch model (porcine), comparing pasteformulated with citric acid cross-linked CMC (CMC-CA) andnon-cross-linked CMC. The testing was performed as follows inheparinized animals. The animal (pig) was injected with heparin toinhibit the blood coagulation system. An 8-mm punch hole wound was madeon the liver. The evaluated hemostatic paste was then applied into thepunch hole wound and pressed with gauze for 1 minute. The gauze wasremoved to observe whether hemostasis is achieved. Extend theobservation time up to 30 minutes to evaluate the effectiveness of thehemostatic paste.

Referring to FIG. 16, the testing results of the hemostatic pasteformulated as described in Example 1, but using non-cross-linked CMC, ispresented (comparative example). Non-crosslinked CMC hemostatic pastewas applied into the punch wound, and hemostasis was achieved in 1minute, as shown. However, re-bleeding was observed at around 30minutes, as shown. Potentially due to partial dissolution ofnon-cross-linked CMC in blood or plasma, the paste gradually lost itsmechanical strength. It is observed that the interface of paste with thetissue dissociated, potentially resulting in re-bleeding. Thus, thenon-crosslinked CMC hemostatic paste has failed in longer termhemostatic evaluation.

Referring to FIG. 17, the testing results of the hemostatic pasteformulated as described in Example 1, using CMC-CA, is presented(inventive example). The inventive hemostatic paste achieved hemostasisin under 1 minute, as shown, in heparinized liver punch model. After 30minutes, no re-bleeding was observed. Thus, the instant crosslinkedCMC-CA based paste exhibited superior hemostatic properties due to its3D polymer net structure with better mechanical and dissolution strengthcompared with pure non-cross-linked CMC.

Example 9. Hemostatic Paste Properties in Animal Model: Hemostasis Datafor Cross-Linked Starch Vs. Cross-Linked CMC Based Paste

The hemostatic paste formulated as described in Example 1 was furtherevaluated in liver punch model (porcine), comparing the inventive pasteformulated with citric acid cross-linked CMC (CMC-CA) and paste withCMC-CA xerogel replaced with the cross-linked starch.

Referring to FIG. 18, the testing results of the hemostatic pasteformulated as described in Example 1, but using CA cross-linkedcarboxymethyl starch, is presented (comparative example). Citric acidcross-linked carboxymethyl starch paste was applied onto the liver punchmodel. While it has achieved hemostasis at 1 min, continuing observationfor 30 minutes indicated that the comparative paste became dry and beganto dissociate with the liver tissue. Further it was shown that it wasrelatively easy to remove the paste compact from the punch hole with atweezer. To the contrary, the inventive CMC-CA based paste does notexhibit this dissociation from tissue phenomenon even after 30 min, asshown in FIG. 17. Based on this evaluation, the inventive crosslinkedCMC-CA based paste exhibited superior hemostatic properties whencompared to cross-linked starch based paste which showed poor tissueadhesion.

Example 10. Hemostatic Paste Adhesion to the Tissue: Comparative Testing

Referring now to FIG. 19, testing the adhesion to the tissue was furtherevaluated as follows. The inventive CMC-CA based hemostatic paste andcomparative hemostatic pastes were applied onto backing materials,including commercially available Oxidized Regenerated Cellulose(ORC)-based non-woven pad and synthetic polymer polyglactin 910(copolymer made from 90% glycolide and 10% L-lactide, PG910)-basednon-woven pad, as shown. Then the patches were applied to the porcineliver tissue. After a 1 min tamponade by hand, the patches were peeledoff from the liver tissue by forceps. The peeling force, whichrepresented the adhesive force of each hydrogel, was evaluated and wasranked from 1 to 5. Referring to Table 6, adhesiveness evaluations arepresented, with 5 being most adhesive; 1 being not adhesive, for theinventive CMC-CA based paste, and for comparative pastes based onpregelatinized starch hydrogel and on CMC-CA/pregelatinized starch 1:1mixture.

TABLE 6 Tissue adhesiveness evaluation (5-most adhesive; 1-not adhesive)Sample Adhesiveness CMC-CA hydrogel based paste (inventive) 5Pregelatinized starch hydrogel (comparative) 2 CMC-CA/pregelatinizedstarch 1:1 3 (comparative)

Based on this evaluation, the inventive crosslinked CMC-CA based pasteexhibited superior hemostatic properties of tissue adhesion whencompared to Pregelatinized starch hydrogel based paste andCMC-CA/pregelatinized starch 1:1 based pastes.

Example 11. Hemostatic Paste Properties in Animal Model

The hemostatic paste formulated as described in Example 1 was furtherevaluated in liver punch model (porcine). Referring to FIG. 20,inventive CMC-CA based hemostatic paste is shown prior, duringapplication, and after application into liver punch model, as pressedinto narrow wound, with the hemostasis achieved within 1 min.

Example 12. Hemostatic Paste on a Substrate—Properties in Animal Model

The inventive CMC-CA based hemostatic paste was applied onto backingmaterials comprising a pad or a gauze for applications onto broaderareas of tissue to address surface bleeding or oozing. Referring now toFIG. 21 inventive CMC-CA based hemostatic paste is shown applied tocommercially available Oxidized Regenerated Cellulose (ORC)-basednon-woven pad. Referring now to FIG. 22, the resulting composite isshown prior to being tested for adhesion to a liver tissue coupon, andafter contacting with liver tissue coupon.

Having shown and described various versions in the present disclosure,further adaptations of the methods and systems described herein may beaccomplished by appropriate modifications by one of ordinary skill inthe art without departing from the scope of the present invention.Several of such potential modifications have been mentioned, and otherswill be apparent to those skilled in the art. For instance, theexamples, versions, geometrics, materials, dimensions, ratios, steps,and the like discussed above are illustrative and are not required.Accordingly, the scope of the present invention should be considered interms of the following claims and is understood not to be limited to thedetails of structure and operation shown and described in thespecification and drawings.

We claim:
 1. A flowable hemostatic paste comprising: A xerogelcrosslinked milled polysaccharide dispersed within a substantiallyanhydrous blend of: i. A glycerol-containing dispersant, and ii. Analcohol-functionalized dispersant selected from the group consisting ofpropylene glycol and 1,3-Butanediol or mixtures thereof, wherein thepaste has a moderate viscosity at rest and room temperature and providesa substantially homogenous dispersion of the crosslinked polysaccharide,and wherein: (i) said paste comprises a weight ratio of propylene glycolto glycerol of from about 1:0.5 to about 1:2; (ii) said paste furthercomprises an alkaline agent; and/or (iii) the weight ratio ofcross-linked polysaccharide to glycerol-containing dispersant rangesfrom about 0.9 to about 1.25.
 2. The hemostatic paste of claim 1,wherein said alkaline agent comprises sodium hydroxide, present at about0.1-3%.
 3. The hemostatic paste of claim 1, wherein the crosslinkedpolysaccharide comprises a carboxymethyl cellulose (CMC) that iscross-linked by reaction via a polyfunctional carboxylic acid, whereinsaid acid is selected from the group consisting of malic, tartaric,citric, malonic, succinic, glutaric, or adipic acid or mixtures thereof.4. The hemostatic paste of claim 3, wherein said acid is citric acid. 5.The hemostatic paste of claim 4, wherein said paste comprises: 35% to65% by weight of citric acid cross-linked CMC, which is suspended ordispersed in powder form in a viscous liquid mixture of aglycerol-containing hygroscopic dispersant and an alcohol-functionalizeddispersant of: propylene glycol, 1,3-Butanediol or mixtures thereof. 6.The hemostatic paste of claim 5, wherein said cross-linked CMC is asuspended powder having average particle size less than 100 microns. 7.The hemostatic paste of claim 6, wherein said paste comprises less than1% of water.
 8. The hemostatic paste of claim 6, wherein said pastecomprises a. about 49-55% of citric acid cross-linked CMC; b. about18-30% of glycerol; c. about 15-30% of propylene glycol.
 9. Thehemostatic paste of claim 6, wherein said paste is supported on asubstrate that is a flexible bioabsorbable sheet.
 10. The hemostaticpaste of claim 9, wherein said substrate comprises oxidized cellulose orpolyglactin
 910. 11. The hemostatic paste of claim 6, wherein said pasteis disposed in a squeezable tube.
 12. A method of making a wounddressing containing the hemostatic paste of claim 6, comprising thesteps of applying said hemostatic paste onto at least one face of aflexible bioabsorbable sheet substrate.
 13. A method of making a wounddressing according to claim 12, wherein the flexible bioabsorbable sheetis in the form of a woven mesh, structured felt, unstructured felt,film, powder or combinations thereof, and contains one or more layers ofoxidized cellulose, hemostatic polymeric blends, or mixtures thereof.14. A method of using the hemostatic paste of claim 6, comprising thesteps of applying said hemostatic paste, optionally supported on aflexible absorbable sheet substrate, to a bleeding tissue or wound.